Vice President Joe Biden is set to arrive in Tokyo tomorrow on a weeklong trip to Asia, which is watching carefully to see how committed the Obama administration is to increasing America’s influence in the region as a hedge against an increasingly assertive China.

In meetings with leaders in Japan, China and South Korea, the vice president will seek to show that while the administration has been preoccupied with Mideast flare-ups and a series of domestic distractions, the United States remained determined to be a Pacific power.

At the same time, disputes among Asian nations seem to be boiling over, threatening instability in a region that’s vital to the U.S. economy.

American allies Japan and South Korea are barely speaking. China is butting heads with its neighbors and with the United States about Beijing’s new air defense zone over a group of tiny islands that has exacerbated long-simmering territorial conflicts. The United States on Friday advised American carriers to comply with China’s demand that it be told of any flights passing through that defense zone.

Early in his first term, President Barack Obama declared the United States was “all in” when it came to the Asia-Pacific region. His administration pledged to increase its influence, resources and diplomatic outreach in the region, and to bolster the U.S. military footprint so that by 2020, 60 percent of the navy’s warships would be based there, compared to 50 percent now.

The concern was that as China came into its own as a superpower, its sway over other Asian nations would grow, too.

But in Obama’s second term, Iran, Syria and Egypt have absorbed the president’s attention on foreign policy matters. At home, the administration has been consumed with a health care rollout that’s become a major political problem, while intense gridlock in Congress has bogged Obama down in domestic disputes.

To cap it off, Obama had to scrap a much-anticipated trip to Asia in October because the federal government was shut down. His absence led many in the region to wonder if it remained an Obama priority.

National Security Adviser Susan Rice said recently it does. She announced that Obama will visit Asia in April and promised that the United States will keep deepening its commitment to Asia “no matter how many hot spots emerge elsewhere.”

But Rep. Steve Chabot said he’s heard loud concerns as he’s traveled the region as the chairman of the House subcommittee dealing with Asia.

“In each country I’ve gotten this feedback: ‘When do you think the president is going to put some meat on the bones?’” Chabot said. “It’s been mostly just talk, and mostly diplomatic engagement. They want to get beyond just talk.”

On his first stop, Biden will meet with Japanese Prime Minister Shinzo Abe before focusing on women’s issues with the new U.S. ambassador, Caroline Kennedy. In Beijing, Biden will meet with Chinese President Xi Jinping, Vice President Li Yuanchao, and Premier Li Keqiang.

After meeting with South Korean leaders in Seoul, Biden will give a major speech on the U.S.-Korea relationship at Yonsei University and lay a wreath at a cemetery honoring fallen U.S. troops.

The trip comes at a critical time. The United States is trying to complete a major trade agreement by year’s end, but it’s not certain the deadline with be honored. The Trans-Pacific Partnership involving the United States, Japan and 10 other nations could clear the way for much greater trade with Asia, in line with Obama’s ambitious goal to double U.S. exports by 2015.

For Xi and Biden, their visit will be something of a reunion. The two exchanged official visits when Xi was vice president, spending hours together as the United States tried to learn as much as possible about the man who would become party leader in 2012.

Biden’s visit comes two weeks after China’s leaders outlined a market reform plan that could be the country’s most significant economic overhaul in at least two decades. The Communist Party conference marked the unveiling of Xi’s vision.

But China’s new air defense zone over the East China Sea may overshadow Biden’s mission. The administration said Biden would raise the issue directly with Chinese leaders.

China announced last week that all aircraft entering the zone — a maritime area between China, Taiwan, South Korea and Japan — must notify Chinese authorities beforehand and that it would take unspecified defensive measures against those that don’t comply.

Neighboring countries and the United States have said they will not honor the new zone, which is believed aimed at claiming disputed territory, and have said it unnecessarily raises tensions.

China’s defense ministry said fighter jets identified and monitored the two U.S. reconnaissance aircraft and a mix of 10 Japanese early warning, reconnaissance and fighter planes during their flights through the zone early Friday.

The United States has tried to stay out of such territorial disputes, but treaty obligations to Japan sometimes get in the way. As China, Japan and others adopt increasingly aggressive stances, the United States worries about an increased likelihood of a mishap spiraling quickly out of control.

In South Korea, the nuclear threat from an unpredictable North Korea is a chief item on Biden’s agenda.

The deal the United States helped strike with Iran to temporarily freeze its nuclear program is a stark reminder of the impasse in negotiations with North Korea. Unlike Iran, North Korea is believed to already have a nuclear bomb, and there’s evidence it is pressing ahead with weapons development.

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